Aldosterone overproduction increases arterial wall stiffness by accumulation of different types of collagen fibres and growth factors. Our previous studies showed that central (aortic) arterial stiffness is increased in primary aldosteronism (PA) independently of concomitant hypertension and that these changes might be reversible after successful adrenalectomy. There is limited data available on the potential impact of mineralocorticoid overproduction on the deterioration of peripheral arterial stiffness. The current study was thus aimed at investigating the effect of aldosterone overproduction on peripheral arterial stiffness assessed by peripheral (femoralankle) pulse wave velocity (PWV) in PA patients compared with essential hypertension (EH) patients. Forty-nine patients with confirmed PA and 49 patients with EH were matched for age, blood pressure, body mass index, lipid profile, and fasting glucose. PWV was obtained using the Sphygmocor applanation tonometer. Both peripheral and central PWV were significantly higher in PA patients compared to EH patients, while clinical blood pressures were similar. Plasma aldosterone level was the main predictor of peripheral PWV in PA. Our data indicate aldosterone overproduction in PA does not preferentially affect central arterial system. Fibroproliferative effect of higher aldosterone levels lead to alteration of central-elastic as well as peripheral-muscular arteries with subsequent increase in its stiffness., J. Rosa ... [et al.]., and Obsahuje seznam literatury
Extensive osteolysis adjacent to orthopedic implants is often associated with wear particles of prosthetic material. The activation of the RANKL/RANK/OPG system is considered to be a likely cause of periprosthetic osteolysis leading to implant failure. The aim of this study was to examine the possible correlation between the clinical extent of osteolysis, the number of wear particles and expression of the osteoclastic mediator RANKL (receptor activator of nuclear factor kappa B ligand) in the tissues aro und aseptically loosened cemented and non-cemented total hip replacements. Periprosthetic tissues were harvested from 59 patients undergoing revision of hip replacement for aseptic loosening. We observed RANKL-positive cells in 23 of our 59 patients, their presence was noted predominantly in tissues with a loosened cemented endoprosthesis. We have found that RANKL is present only in tissues with a large amount of wear debris and predominantly in cases involving loosened cemented implants., D. Veigl, J. Niederlová, O. Kryštůfková., and Obsahuje bibliografii a bibliografické odkazy
High levels of catecholamines in pheochromocytoma (PHEO) are associated with risk of cardiovascular complications. In this study, we looked for potential differences in markers of oxidative stress – vitamin C, superoxide dismutase (SOD) and malondialdehyde (MDA) in PHEO before and after the operation. We studied 18 subjects with PHEO who were examined before and approximately one year after the successful tumor removal (free of disease). All subjects had elevated urinary epinephrine and/or norepinephrine levels before the operation. Vitamin C levels increased significantly after the operation from 61±27 to 77±20 μmol/l (P=0.02), and MDA decreased significantly after the tumor removal from 2.6±0.4 to 2.0±0.6 μmol/l (P=0.01). However, no changes were found in SOD activity before and after the operation. In conclusion, increased catecholamine production in PHEO is accompanied by decreased levels of vitamin C and increased levels of MDA which may indicate the activation of oxidative stress in PHEO. Successful operation was associated with lowering of oxidative stress by using both biomarkers. On the contrary, no changes in SOD activity before and after the tumor removal were noted., H. Turková, ... [et al.]., and Obsahuje seznam literatury
Although statins exert non-lipid cardioprotective effects, their influence on cell death is not fully elucidated. For this purpose, we investigated whether simvastatin treatment (S, 10 mg/kg, 5 days) is capable of mitigating ischemia/reperfusion-induced (IR) apoptosis in the isolated rat hearts, which was examined using immunoblotting analysis. In addition, the content of signal transducer and activator of transcription 3 (STAT3) and its active form, phosphorylated STAT3 (pSTAT3-Thr705), was analyzed. Simvastatin induced neither variations in the plasma lipid levels nor alterations in the baseline content of analysed proteins with the exception of upregulation of cytochrome C. Furthermore, simvastatin significantly increased the baseline levels of pSTAT3 in contrast to the control group. In the IR hearts, simvastatin reduced the expression of Bax and non-cleaved caspase-3. In these hearts, phosphorylation of STAT3 did not differ in comparison to the non-treated IR group, however total STAT3 content was slightly increased. The improved recovery of left ventricular developed pressure co-existed with the increased Bcl- 2/Bax ratio. In conclusion, pleiotropic action of statins may ameliorate viability of cardiomyocytes by favouring the expression of anti-apoptotic Bcl-2 and downregulating the proapoptotic markers; however STAT3 does not seem to be a dominant regulator of this anti-apoptotic action of simvastatin., T. Rajtík, ... [et al.]., and Obsahuje seznam literatury
The activation of metabotropic glutamate receptors subtype 4 (mGluR4) potentiates models of absence seizures in adult rats. These seizures are age-dependent, but data concerning the role of mGluR4 in immature brain is insufficient. N-phenyl-7- (hydroxyimino)cyclopropa[b]chromen-1acarboxamide (PHCCC), which is a positive allosteric modulator of these receptors, was used in three different models of seizures in immature rats: 1) convulsions induced by high doses of pentetrazol (PTZ; a model of generalised tonic-clonic seizures); 2) rhythmic electroencephalographic (EEG) activity induced by low doses of PTZ (a model of absence seizures); and 3) electrically elicited cortical afterdischarges (ADs, a model of myoclonic seizures). We administered four doses of PHCCC (1, 3, 10 and 20 mg/kg) in PTZ-induced convulsions and two doses (3 and 10 mg/kg) in the two electrophysiological models of freely moving rats with implanted electrodes. Every dose and age group consisted from 8 to 10 rats. PTZ-elicited convulsions were not significantly influenced by PHCCC. In contrast, PHCCC potentiated the effect of a subconvulsant dose (60 mg/kg) of PTZ. The 10-mg/kg dose of PHCCC significantly prolonged the duration of PTZ-induced rhythmic activity episodes and shortened the intervals between individual episodes in 25-day-old rats (P25). In contrast, this potentiation was not seen in P18 rats. Cortical ADs were significantly prolonged with repeated stimulations by both doses of PHCCC in P12 and P18 animals. P25 rats exhibited only slightly longer AD durations. In conclusion, we did not find any anticonvulsant effect of PHCCC. On the contrary, proconvulsant action was demonstrated in all three models in immature rats., E. Szczurowska, P. Mareš., and Obsahuje seznam literatury
Exposure to chronic hypoxia results in hypoxic pulmonary hypertension characterized by structural remodeling of peripheral pulmonary vasculature. An important part of this remodeling is an increase of collagen turnover and deposition of newly formed collagen fibrils in the vascular walls. The activity of collagenolytic metalloproteinases in the lung tissue is notably increased in the first days of exposure to hypoxia. The increased collagenolytic activity results in the appearance of collagen cleavages, which may be implied in the triggering of mesenchymal proliferation in peripheral pulmonary arteries. We hypothesize that radical injury to pulmonary vascular walls is involved in collagenolytic metalloproteinase activation., J. Novotná, J. Herget., and Obsahuje bibliografii
Preadipocyte factor-1 (Pref-1) is a member of epidermal growthfactor like family of proteins that regulates adipocyte and osteoblast differentiation. Experimental studies suggest that circulating Pref-1 levels may be also involved in the regulation of lipid and glucose metabolism and energy homeostasis. We hypothesized that alterations in Pref-1 levels may contribute to the ethiopathogenesis of anorexia nervosa or its underlying metabolic abnormalities. We measured Pref-1 concentrations and other hormonal, biochemical and anthropometric parameters in eighteen patients with anorexia nervosa and sixteen healthy women and studied the influence of partial realimentation of anorexia nervosa patients on these parameters. The mean duration of realimentation period was 46±2 days. At baseline, anorexia nervosa patients had significantly decreased body mass index, body weight, body fat content, fasting glucose, serum insulin, TSH, free T4, leptin and total protein. Partial realimentation improved these parameters. Baseline serum Pref-1 levels did not significantly differ between anorexia nervosa and control group (0.26±0.02 vs. 0.32±0.05 ng/ml, p=0.295) but partial realimentation significantly increased circulating Pref-1 levels (0.35±0.04 vs. 0.26±0.02 ng/ml, p<0.05). Postrealimentation Pref-1 levels significantly positively correlated with the change of body mass index after realimentation (r=0.49, p<0.05). We conclude that alterations in Pref-1 are not involved in the ethiopathogenesis of anorexia nervosa but its changes after partial realimentation could be involved in the regulation of adipose tissue expansion after realimentation., P. Kaválková ... [et al.]., and Obsahuje seznam literatury
a1_A new concept of cardioprotection based on the exploitation of endogenous mechanisms is known as ischemic preconditioning (IPC). It has been hypothesized that substances released during brief ischemic stress (e.g. catecholamines) stimulate the receptors and trigger multiple cell signaling cascades. Opening of ATP-sensitive K+ channels [K(ATP)] has been suggested as a possible final step in the mechanisms of protection. In this study, the role of adrenergic activation was tested in Langendorff-perfused rat hearts subjected to test ischemia (TI; 30 min occlusion of LAD coronary artery) by: 1) mimicking IPC (5 min ischemia, 10 min reperfusion) with short-term (5 min) administration of norepinephrine (NE, 1 µM), 15 min prior to TI; 2) blockade with b- or a1-receptor antagonists, propranolol (10 µM) and prazosin (2 µM), respectively, applied 15 min prior to TI during IPC. The role of K(ATP) opening was examined by perfusion with a K(ATP) blocker glibenclamide (10 mM) during IPC. Both IPC and NE-induced PC effectively reduced the incidence of ventricular tachycardia (VT) to 33 % and 37 %, respectively, vs 100 % in the non-PC controls, whereby ventricular fibrillation (VF) was totally abolished by IPC and markedly suppressed by PC with NE (0 % and 10 %, respectively, vs 70 % in the non-PC hearts; P<0.05). The severity of arrhythmias (arrhythmia score, AS) was also markedly attenuated by both interventions (IPC: AS 1.7±0.4; NE-PC: AS 1.8±0.3 vs AS 4.1±0.2 in the controls; P<0.05). Protection was not suppressed by propranolol (VT 28 %; VF 14 %; AS 2.2±0.6), whereas prazosin reversed the protective effect of PC (VT 83 %; VF 67 %; AS 4.0±0.8). Antiarrhythmic protection afforded by NE-PC was abolished by pretreatment of rats with pertussis toxin (25 mg/kg, i.p.) given 48 h prior to the experiments., a2_Glibenclamide did not suppress the IPC-induced protection. In conclusion, the sensitivity of the rat heart to ischemic arrhythmias can be modulated by IPC. Protection is mediated via stimulation of a1-adrenergic receptors coupled with Gi-proteins but glibenclamide-sensitive K(ATP) channels do not appear to be involved in the mechanisms of antiarrhythmic protection in this model., T. Ravingerová, D. Pancza, A. Ziegelhoffer, J. Styk., and Obsahuje bibliografii